The Stovebolt Site Forums The Shop Area Driveline Hydramatic Question

I am trying to find tdc on the 235 in my 54 chev. I jacked up one back wheel to see if I can turn the engine that way and am only able to get it to engage is in reverse.Is there a better way to do this? Last time I just pulled the starter and pried on the ring gear to turn the engine. Thanks

Is there something about the transmission that stops you from turning it over using the fan?

You should not be able to turn the driveshaft in reverse with engine not running. Reverse is actually like a park in that there is a big pawl that locks into drive gear when there is no fluid pressure. Take trucker's advice and pull the sparkplugs and turn it with the fan. Remember there are two crank rotations per cam rotation so that if you are looking for TDC with number 1 firing, you will need to know that the valves are closed for #1 when at TDC timing mark.

Do you have the shift/gear/range selector lever in Neutral, with the ignition-key on?

I tried turning with the plugs out and trans. in neutral, belt just slips.Is there a reason key needs to be on?

when you turn it by the fan you need to use one hand to tighten the belt to the max so it can't slip

Bill

No reason for key to be on. I don't understand that one either.

Are you just trying to see of motor is locked or what?

Thanks all I got it turning , if I needed it any tighter it would take a new fan belt.The problem all started when I replaced the vacuum advance and seem to have put the dist. back wrong.

FYI, the shop manual for my 55 S2 with Hydra says you can roll start the truck by getting it going about 20 mph in neutral then dropping it down into 4-1 or 3-1. Also, it verifies that reverse when the engine is turned of becomes park. Not sure if this is a mechanical park or what.

It pretty much locks solid. If you imagine the shaft in the transmission tied to reverse that the driveshaft hooks to, and at the back of it, there is a large "gear" with big teeth in it, and a lock pawl that drops into the teeth of that gear and keeps the shaft from being able to turn, you have it down in it's basics. When there is throttle pressure, meaning the engine is running, that pressure holds the lock pawl away from the gear teeth.

I dont know if you want to drop it into gear while its rolling, best to put it in first gear and roll it.

"Should it become necessary to start the engine by pushing the truck, a method similar to that used with a conventional transmission is best utilized. The transmission is kept in Neutral until a vehicle speed of twenty miles per hour is maintained, at which point the driver shifts into the 1-4 range."

I'd think you would only want to do this with an engine that you sure is not locked/seized.

yes, i checked my several manuals and you are correct.

a couple of them also say dont push or roll start a hydro vehicle with less than 5000 miles on its rebuilt tranny

Hydro?